This invention relates, in general, to ultra precise apparatus for fabricating a diamond tool and is particularly concerned with a machine for forming a complex profiled face on such a tool.
Precision diamond tools are typically formed by mounting a diamond blank in a tool holder and then presenting the blank to a grinding device, such as a diamond wheel, which is supported for high speed rotation. The blank is brought to bear against the surface of the wheel until a desired profile is formed on the face of the blank. By and large this is a manual operation entailing countless passes of the blank against the cutting wheel in attempting to match the desired profile.
A diamond tool of the type herein considered finds particular application in fashioning the tooling required to form intricately contoured molds, such as the mold used for producing a projection television screen of the type characterized by a multiplicity of lenticules disposed in a precision array for the purpose of directing and focusing the television image projected thereon toward a viewer. Such a projection screen is disclosed in copending application Ser. No. 265,938 which was filed on May 21, 1981 in the name of Howard G. Lange, which application is assigned to the same assignee as the present invention. Any imperfections in forming the screen will result in a readily discernible degradation of the image or, reduced or uneven brightness due to uneven distribution of the image light through the screen. Accordingly, the tool for forming the mold master must be very precise; in practice, the tool should have a tolerance in the order of a few microinches. Prior art diamond tool forming arrangements have failed to provide the precision desired.
U.S. Pat. No. 3,813,818-Hayashi et al disclose a profile grinder which has an abrasive grinding wheel adapted to move laterally for controlling the depth of abrasion in response to a follower maintained in contact with a template.
Ulfves discloses in U.S. Pat. No. 2,716,851 a cam controlled work holder. Its contribution to the art is said to reside in the use of extra cams to permit grinding of tapers, angles, ovals, etc. However, the structure and method of operation of the aforementioned disclosures is very different from our invention, and neither is capable of achieving the precision grinding attainable by the apparatus described herein. Other prior art uncovered in a search included U.S. Pat. No. 3,251,157 and U.S. Pat. No. 4,068,413 which also were studied but deemed inapplicable to the invention described herein.